This invention relates generally to the field of vehicle seating where comfort, durability, efficiency in production and recyclability are important goals. This invention uses a novel process to create a multiple density body of thermoplastic polymer fibers.
Recently, improved materials have been developed in the field of vehicle seat components such as thermoplastic polymeric fibers. Seat components made from these thermoplastic fibers are more breathable than the traditional polyurethane foam and are also more easily recyclable. However, there is room for improvement in the support provided by seats made from the thermoplastic fibers. Thermoplastic fiber bodies with zones of different densities have been shown to improve the support, comfort and durability of vehicle seats. In the current invention, improved techniques for creating high and low density zones in a body of a vehicle seat component are described.
Conventional foam vehicle seats have been made with multiple density zones as disclosed in U.S. Pat. No. 5,000,515, issued Mar. 19, 1991 to Deview, entitled "Variable Density Foam Vehicle Seat". In this method, expandable foam is injected into a mold cavity where the mold cavity is partitioned into density zones using cloth barriers. Expandable foam materials of differing densities are used. The foam with the appropriate density is injected into each zone.
In contrast, the current invention does not require two chemically different fill materials. Instead, the higher density zones of this invention simply contain more polymeric fibers relative to the zone volume than the lower density zones. Therefore the manufacturing process for this invention will require less chemical processing than the multiple density foam vehicle seat disclosed in U.S. Pat. No. 5,000,515. Additional advantages such as recyclability, improved breathability and the ability to use a very efficient one-step process are inherent in the choice of polymeric fibers over polyurethane foam for the body of a vehicle seat component.